Resting-state Functional Connectivity Is Related To Age-associated Decreases In Physical Activity Engagement

PURPOSE: Physical inactivity is a global pandemic, especially in the older adult population, who report more barriers to physical activity (PA) engagement. The current analysis aims to understand the neural mechanisms underlying PA engagement change across the lifespan, which can provide insight into strategies to maintain or promote PA with age. METHODS: The current analyses involved data from the Cambridge Centre for Ageing and Neuroscience (CAM-CAN) dataset. Participants aged 18-80 years completed a self-reported PA questionnaire and a resting-state functional MRI. First, piecewise regression revealed that PA was stable until 52 years old when it began decreasing. Second, we identified seed-based functional connectivity associating with PA for individuals over 52 (n = 328), by seeding several a priori defined regions of interest, including the bilateral dorsolateral prefrontal (dlPFC), ventromedial prefrontal (vmPFC), dorso-anterior insula (dAI), and anterior cingulate (ACC), based on their association with reward-motivated and self-regulating behaviors in previous studies. RESULTS: We found that connectivity between ACC and vmPFC, and the dAI and supplementary cortex, middle cingulate, vmPFC, supramarginal gyrus, and cerebellum were associated with PA (FWE corrected Cluster p < 0.05, Voxel p < 0.001). Finally, we tested the mediating role of these functional connections on the association between age and decline in PA engagement after age 52. Mediation models were tested with 1000 bootstrap and False Discovery Correction was applied for all six pairs of functional connections. We found indirect effects of age on PA engagement via connectivity between dAI and supplementary cortex (β = -0.07, p = 0.012), right supramarginal gyrus (β = -0.06, p = 0.027), left supramarginal gyrus (β = -0.04, p = 0.034), vmPFC (β = -0.04, p = 0.032), and between ACC and vmPFC (β = -0.09, p = 0.005) significantly mediated the negative relationship between age and PA engagement. CONCLUSIONS: The findings suggest that age-related functional alteration in brain regions which support self-regulation may lead to decreased engagement in PA among middle-aged-to-older adults. Interventions targeting these neural circuits might be helpful for promoting adherence to PA in the future.